JPS6397669A - Paint for plastic - Google Patents

Abstract

PURPOSE:To provide the title paint which has excellent adhesion to the surfaces of molded products of plastics and gives a coating film having excellent surface properties, by dissolving or suspending a dye, a specified synthetic resin and an epoxysilane compd. in a solvent. CONSTITUTION:A mixture of an alpha,beta-unsaturated carboxylic acid (a) and a lower alkyl ester (b) of said acid is polymerized with optionally an equal or less amount of a vinyl monomer (c) copolymerizable with the components (a) and (b) to obtain a synthetic resin (A) having an MW of 5,000-100,000, an alkyl alpha,beta-unsaturated carboxylate monomer unit, a carboxyl group content of 2.5-40wt% and a group capable of bonding to an epoxy group. 100pts.wt. component A, 0.5-30pts.wt. colorant (B) which is a pigment or a dye, and 10-200pts.wt. epoxysilane compd. (C) of the formula (wherein R1 is a 1-10C bivalent hydrocarbon group or a 2-10C bivalent hydrocarbon group having at least one ether linkage; R2 and R3 are each a 1-5C hydrocarbon group; m is 0-1; and n is 0-2) are dissolved or suspended in 30-400pts.wt. solvent (D).

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a paint for plastics, and more specifically, to paints for plastic molded products such as polypropylene resin, polyethylene resin, polyester resin, polycarbonate resin, polyamide resin, polyphenylene oxide resin, etc. The present invention relates to a novel paint for plastics that is useful for painting and provides beautiful and excellent surface properties.

(Prior Art) Conventionally, many plastic molded products have been used as automobile parts, building materials, general consumption materials, and the like. As a method for coloring and improving the surface properties of these plastic moldings, at the time of molding the plastic molding or at the stage before that,
There are methods of kneading pigments and fillers into plastics, and methods of applying paint to the surface of plastics after molding to form a film.

(Problems to be solved by the invention) The method using the above-mentioned paint for plastics does not require equipment such as a large crosstalk machine, requires less coloring agent, and requires less molding surface. Although this method is very convenient in that it can only be colored, the biggest problem is that the adhesion of the coating film is extremely poor for molded products made of non-polar plastics such as polypropylene resin. Various methods have been proposed to solve these drawbacks, including a method in which the surface of a plastic molded product is subjected to a corona discharge treatment before painting, and a method in which various types of brimers are used.

However, all of the above methods require various equipment and are complicated, so they are extremely disadvantageous in terms of process.
Still sufficient I: At present, satisfactory adhesion of the coating film has not been achieved.

Therefore, there is no need to specially treat the surface of the plastic molded product or use a two-component type brimer.
There is a need for a coating for plastics that can provide a coating with excellent adhesion and surface properties to the surface of plastic molded articles.

(Means for Solving the Problems) As a result of intensive research in order to meet the demands of the prior art as described above, the present inventor used a specific synthetic resin as a film-forming agent, and added specific additives to this film-forming resin. The present invention was completed based on the finding that when a paint is prepared by combining these agents, the paint is useful as a paint for plastics that satisfactorily solves the various problems mentioned above.

That is, the present invention is a paint for plastics characterized by dissolving or suspending each component of a dye, a synthetic resin having a group capable of bonding with an epoxy group, and an epoxy silane compound in a solvent.

Next, to explain the present invention in more detail, as the pigment used in the present invention, any conventionally known organic pigment, inorganic pigment, or dye can be used. quinacridone series, anthraquinone series, dioxazine series, indigo/thioindigo series, perinone/perylene series, isoindorenone series,
These include titanium oxide, cadmium, iron oxide, and carbon black. Of course, these pigments may be in powder form, but it is preferable that they remain in the form of an aqueous paste immediately after production.

Any dye may be used. In particular, if dyes with 4T groups that react with epoxy groups such as amino groups, hydroxyl groups, and carboxyl groups are used, the resulting colored film will have higher water resistance and solvent resistance, and there is no risk of dye elution. In that there is no
This is a recommended mode. To give specific examples of such dyes, C, 1, No. of 7th place outside of color in are as follows: 11100, 11110, 11115, 111
18, 11120.11125, 11129,
Ill:10.111:15.11150.

11152, 1118G, 11!90, 111
95.11200.11205, 11210.112
15, 11220, 11225.1123G,
11410, 1142θ, 11430.11435
．． 13056.13058, 13379, 6076
7, 61505.61510, 61540, 61
545, 62065, 62150.62500%6
2505, and other disperse dyes, as well as metal-containing organic dyes disclosed in the following prior patent documents: JP-A-49-32924, JP-A-50-9631, JP-A-49-130921 , JP-A-50-10323, JP-A-50-3498, JP-A-50-38793, JP-A-50-6695, JP-A-50-38794, JP-A-Sho 50 -123146, JP-A-51-25528, JP-A-50-156541, etc. In addition, various dyes containing sulfonic acid groups or carboxyl groups, such as direct dyes, acid dyes, and oil-soluble dyes, have primary to tertiary amino groups, or quaternary ammonium salts, and Pigments made into dye salts by reacting with compounds having groups capable of reacting and bonding with epoxy groups, such as amino alcohols and diamines, can also be used.

The amount of pigment to be incorporated into the paint for plastics of the present invention varies depending on how much color density is desired to be imparted to the colored film to be formed; The ratio is about 0.5 to 30 parts by weight per 100 parts by weight of the 2-forming resin. .

The resin used as a film forming agent in the present invention is a synthetic resin having a group capable of bonding with an epoxy group, and the groups capable of bonding with an epoxy group include a hydroxy group, halogen, carboxyl group and its derivatives, aldehyde, carbonyl group, etc. A synthetic resin that has a group that can bond with an epoxy group is nothing but a thermoplastic or thermosetting synthetic resin that has any of these groups in its molecule! +j',
IC erection.

+1.1 Among such synthetic resins, the most useful for the purposes of the present invention are vinyl addition polymers having carboxyl groups. This type of synthetic resin has excellent properties as a colored film formed on a plastic molded article, and is easy to manufacture.

The introduction of a carboxyl group into a vinyl addition polymer can be carried out using α,
This is achieved by polymerizing using a β-unsaturated carboxylic acid monomer. These α,β-unsaturated carboxylic acids are preferably copolymerized with lower alcohol esters, such as methyl, ethyl, propyl or butyl esters, rather than being used alone for reasons described below.

The composition for obtaining the synthetic resin used in the present invention may include only the above two components, that is, α,β-unsaturated carboxylic acid and its ester, but may also include a third component such as styrene, acrylonitrile, Vinylidene chloride, α, β-unsaturated carboxylic acid esters other than those listed above, vinyl acetate, vinyl chloride, acrylamide, methacrylamide, and vinyls such as droxyethyl methacrylate, hydroxypropyl methacrylate, N-methylolacrylamide, N-butoxymethylacrylamide, etc. An interpolymer may be formed in the presence of monomers. however,
The ht of the vinyl monomer is preferably equal to or less by weight with respect to the total amount of the α,β-unsaturated carboxylic acid and its lower alkyl ester.

The carboxyl group-containing addition polymer may, of course, form an ammonium salt or an amine salt.

When producing the above vinyl addition polymer.

The selection of the proportions of monomers used is important.

That is, it is preferred that the polymer contain one α,β-unsaturated carboxylic acid alkyl ester monomer unit and that the carboxyl groups in the polymer are in the range of about 2.5 to 40% by weight. The weight of carboxyl group is approximately 2.5%
If the amount is less than 1, the amount of the epoxy silane compound that can be chemically bonded to the epoxy silane compound is limited, and as a result, a colored film with sufficient physical properties for the purpose of the present invention cannot be obtained. On the other hand, the higher the weight exceeds about 40%, the higher the water solubility of the resin produced when α,β-unsaturated carboxylic acid is used.
Water resistance and other physical properties of the colored film deteriorate. α,β-unsaturated carboxylic acid alkyl ester is free II! Compared to acids, affinity for dyes, resistance, heat resistance, acid resistance,
On average, it makes an excellent contribution to the various properties required for colored coatings, such as alkali resistance. Therefore, the ratio of the α,β-unsaturated carboxylic acid monomers should be selected within the range that provides a sufficient amount of carboxyl groups to achieve a desirable degree of bonding with the epoxysilane compound.

There is no particular limitation on the molecular weight of the synthetic resin, but if it is too low, the physical properties of the colored film will be unsatisfactory, while if it is too high, the dispersibility of the dye will be poor. Our experience has shown that the preferred molecular weight range is about 5,000 to 100,000.

A synthetic resin having a group capable of bonding with an epoxy group can be produced according to any conventionally known method. For example, α, which gives the synthetic resin having the above carboxyl group,
A monomer mixture consisting of a β-unsaturated carboxylic acid and its ester is polymerized by solution polymerization, emulsion polymerization, or suspension polymerization, using a polymerization regulator if necessary, to obtain a polymer with a preferred molecule of 111. . Alternatively, a method can be employed in which a polymer containing acid anhydride, ester, cyano groups, etc. is first prepared and then these groups are hydrolyzed or saponified to later form carboxyl groups. Even when using an ammonium salt or an amine salt, the salt can be formed at any time.For example, a method of polymerizing using a monomer that is an amine salt of a carboxyl group, etc. A method in which an amine or the like is reacted after mixing or carboxyl group formation such as the above-mentioned hydrolysis, or a method in which an amine or the like is added during or after mixing with the dye can be adopted.

Next, the epoxysilane compound used in the present invention preferably has the following general formula.

ll2G-(:It-(R+), -5i-(OR2)
3-n-(R3).

[In the formula, R is C, -C,. or a C2 to COO divalent hydrocarbon group containing at least one ether bond, R2 and R3 represent a C1 to C5 hydrocarbon group, m is 0 or 1, and n is Oll or 2. ] Among the compounds represented by the above formula, examples of compounds that can be used in the present invention are as follows.

Glycidoxypropyltrimethoxysilane, glycidoxypropyltriethoxysilane, glycidoxypropyltripropoxysilane, glycidoxypropylmethyldimethoxysilane, glycidoxypropyl ethyldimethoxysilane, glycidoxypropyl ethyl silane Toxysilane, glycidoxypropylbutyldimethoxysilane, glycidotrimethoxysilane, glycidotriethoxysilane, glycidobutyldimethoxysilane Preferred compounds not included in the above formula include 2-
(2,3-epoxycyclohexyl)ethyltrimethoxysilane may be mentioned.

The blending ratio of the synthetic resin and the epoxy silane compound shown above depends on various factors such as the content of epoxy groups and groups in the synthetic resin that can react with them, the coating method, the thickness of the coating film, the curing temperature, and economic efficiency. It is determined. Usually, synthetic resin 1
Epoxysilane compound 10-2 to 00 parts
00 parts by weight, and the optimum range is 25-120 parts by weight.

As mentioned above, the plastic paint of the present invention, which has a pigment, a synthetic resin having a group capable of bonding with an epoxy group, and an epoxysilane compound as its basic components, is used in the form of a solution or suspension in an appropriate solvent. It is convenient.

The main solvents are hydrophilic organic solvents, hydrophobic petroleum solvents, or mixtures thereof; examples of the former include methanol, ethanol, propatool, butanol, amyl alcohol, diacet alcohol, dioxane, Acetone, methyl ethyl ketone, methyl isobutyl ketone, formamide, dimethyl formamide, benzy!
V alcohol, methyl acetate, ethyl acetate, butyl acetate.

Examples of the latter include toluene, xylene, and tetrahydrofuran. cumene, n-hebutane, octane,
Examples include decane, decalin, mineral turpentine, and other petroleum distillates. Among these, the most preferred are propatool, butanol, diacetone alcohol, benzyl alcohol, cellosolves, toluene, xylo, mineral turpentine, and the like.

The amount of these organic solvents used varies depending on the manufacturing process of the plastic paint, the method of application to the plastic molded product, etc. Usually, the appropriate amount is 1.30 to 400 parts by weight per 100 parts by weight of the resin content in the paint for plastics.

Regarding solvent systems, by appropriately combining hydrophilic and hydrophobic solvents, it is possible to change the surface condition of the colored film, adjust the applicability to plastic molded products, level the colored film, gloss, etc. properties such as surface condition can be changed appropriately.

Since the plastic paint of the present invention has a limited pot life due to the reaction between the synthetic resin component and the epoxy silane compound component, it is prepared as a two-component combination that separates the two components, and when used, it is necessary to 4 It is desirable to mix.

′,i In this case, a colorant is produced by dispersing the pigment or dissolving the dye in the synthetic resin, adding a solvent if necessary to adjust the solid content of the pigment, and adding an epoxysilane compound to this colorant during use. It is convenient to add and mix uniformly with a solvent and form a paint.

Various methods can be employed to produce the colorant before it is combined with the epoxysilane compound. A typical method is to blend the pigment, resin, and solvent components, and then crush and mix the mixture using a commonly used dispersing machine such as a ball mill, homomixer, sand grinder, speed line mill, or roll mill. When a dye is used instead of a pigment, the dye or a solution of the dye and the amine component may simply be mixed with the synthetic resin component.

The object to which the plastic paint of the present invention can be used is not particularly limited, and may be any plastic, such as polypropylene resin, polyethylene resin, polystyrene resin,
It is a plastic molded product such as polyester resin, polycarbonate resin, polysulfone resin, polyamide resin, polyphenylene oxide resin, etc., and the shape and size of the molded product may be any and are not particularly limited.

In particular, plastic molded articles to which the plastic paint of the present invention provides a film with high adhesion may contain various inorganic fillers, such as calcium carbonate, magnesium carbonate, calcium sulfate, calcium sulfite, magnesium sulfate, calcium phosphate, bases, etc. magnesium carbonate, sodium chloride.

Sodium sulfate, barium carbonate, barium sulfate, aluminum oxide, zinc oxide, magnesium hydroxide, calcium oxide, magnesium oxide, strontium oxide, barium oxide, titanium oxide, alumina, mica, silicic acid, kaolin, talc, clay, shirasu, diatom Above, it is a plastic molded product containing various concentrations of glass powder, zeolite, metal powder, etc.

When the plastic paint of the present invention is applied to a plastic molded article containing such an inorganic filler, the epoxysilane compound in the paint also combines with the inorganic filler present on the surface of the plastic molded article, so that the formed coating is difficult to form. It is possible to provide a colored film that adheres more firmly to objects and is resistant to peeling.

Next, a method of painting a plastic molded article using the plastic paint of the present invention will be described. The method is based on the method of painting a plastic molded article using the plastic paint of the present invention, which is made of an arbitrary pigment, a synthetic resin having a group capable of bonding with an epoxy group, and an epoxy silane compound. A plastic paint is applied to a desired location on the surface of the plastic molded product, and the gap between the synthetic resin and the epoxysilane compound is
and forming a strong colored film by causing a reaction between the epoxysilane compound and the plastic molding (or inorganic filler).

The application of plastic paint to plastic molded products is as follows.
This can be done by various known means.

For example, the viscosity of the plastic paint can be adjusted using an appropriate solvent, and the coating can be applied by methods such as screen printing, gravure printing, and intaglio transfer printing, or by using an applicator or bar coater.

Application may be by means such as spraying, dipping, brushing, brushing, etc.

The reaction between the plastic (or inorganic filler) and the epoxy silane compound can proceed to some extent even if the plastic coating is left to dry at room temperature after application, but for example, when plastic molding is carried out at a temperature of 50°C to 250°C. A colored film with the best physical properties can be obtained by heating to accelerate the reaction within a range that does not cause deformation or deterioration of the object.

In carrying out the above coating method, the paint for plastics is not limited to only the above-mentioned components, and it is of course possible to use other auxiliary materials in combination. It is desirable that such auxiliary materials are useful for the present invention, such as triethylbenzylammonium, which serves as a catalyst to promote the above reaction. Further, any agent can be used as long as it does not impede the object of the present invention, such as various antifoaming agents and leveling agents.

The present invention will be specifically explained below with reference to examples of manufacturing the paint for plastics of the present invention and coloring coating of plastic molded objects using the same.

In the text, "parts" and "%" refer to weight.

Δ Production Examples 1 to 3 The following components were mixed and polymerized at about 65°C for 8 hours. The molecular weight of the obtained polymer is approximately 40,000 to 60,000.
Met.

Ethyl acrylate 20 parts Benzyl acrylate 25 parts Acrylic acid
5 parts azobisisobutyroninoryl 1 part n-butanol
25 parts toluene
25 parts Komatasan Masumatajo ethyl acrylate 5 parts butyl acrylate 10 parts methyl methacrylate 15 parts cyclohexyl methacrylate 10 parts N-methylolacrylamide 5 parts methacrylic acid
5 partsLert-dodecyl mercaptan 0.5
1 part azobisisobutyronitrile 1 part triethylamine 6 parts ethyl cellosolve 44 parts Uni-2-ethylhexyl methacrylate 20 parts acrylic acid 30 parts azobisisobutyronitrile 1 part butyl cellosolve
Production Examples 4 to 6 of 50 parts of ζ No. 6 The following formulations were mixed for 2 hours using a paint shaker to obtain a pigment resin dispersion.

Engineer A, production example 1 is 1! Polymer solution 20 parts Ammonia water (28%) 1 part n-butanol 54 parts Carbon black pigment 20 parts Polymer solution obtained in Production Example 2 10 parts Ethyl cellosolve 58 parts C,1, Pigment Red 5 32 parts Polymer solution obtained in Production Example 3 15 parts Jetanolamine 1 part Butyl cellosolve 10 parts Methyl isobutyl ketone 19 parts Titanium oxide white
55 parts Examples 1 to 3 Plastic paints with the following formulations were prepared, and each of these plastic paints was molded by kneading 20% talc into polypropylene resin (PP) (Noblen, manufactured by Mitsui Toatsu). The molded plate and polyphenylene oxide resin (PPO) (made by Nonyl PX1710. Engineering Plastics) were coated using a 48 bar coater, and in the case of a polypropylene resin molded product, the polyphenylene oxide resin (PPO) was coated at 140°C for 30 minutes. In the case of oxide resin moldings, bake at 100℃ for 30 minutes,
75 parts of the polymer solution obtained in Production Example 1 of Solitary Earthwork Black Painted Board Production Example 4
Black pigment resin dispersion obtained in 50 parts butyl carpitol 5 parts butyl cellosolve
5 part isoproper tool
5 parts methyl isobutyl ketone 5
35 parts of glycidoxypropyltrimethoxysilane 120 parts of the polymer solution obtained in Production Example 2
Red pigment resin dispersion obtained in 40 parts ethyl cellosolve 5 parts isopropanol
5 parts methyl ethyl ketone
10 parts glycidoxypropyltrimethoxysilane 4
0 parts Ingenuity 1. White coated board Polymer solution obtained in Production Example 3 100 parts Production Example 6
White pigment resin dispersion obtained in 100 parts isopropanol 10 parts butyl cellosolve
10 parts Glycidoxypropyltrimethoxysilane 50 parts Comparative test Various tests were conducted on plastic molded articles whose surfaces were colored according to the examples of the present invention according to the following methods. For comparison, tests were also conducted on painted plates of Comparative Examples 1 to 3, which were obtained in the same manner as Examples 1 to 3, except that no epoxysilane compound was used in each of Examples 1 to 3. Ta.

Adhesiveness: A 10×10 cellophane tape peel test was conducted and expressed as the number of stitches remaining without peeling. The evaluation criteria are as follows.

100/100 --------◎(70~99
) / 100------0 (10~69)
/ 100---------△(0~9)/1
00--------- X Solvent resistance: After immersion in methanol and gasoline solvents at room temperature for 24 hours, a cellophane tape peeling test was conducted.

Water resistance: After being immersed in water at room temperature for 30 days, a cellophane tape peel test was conducted.

Hardness: Determined by pencil hardness test.

The results for the north are summarized in the table. It is clear from the data in the table that the paint films according to the invention are significantly superior in adhesion, water resistance, solvent resistance and hardness compared to the comparative examples. Long-term use also confirmed that it had excellent tolerance.

One trigram≧−”6% I II m It/
Vl (IIP) ◎ ◎ ◎ ◎
3111 (11PO) ◎ ◎ ◎
03112 (PP) ◎ ◎ ◎ ◎
3+12 (IIPO) ◎ ◎ ◎
03113 (PP) ◎ ◎ ◎ ◎
4113 (I'PO) ◎ ◎ ◎
Q 411' column xnmrvv 1 (1'P) x x △ x211
t (ppo) △ x x
2112(PP) x x Δ x
2112 (1) PO) Δ x x
x 2113(PP) x x
Δ x 383 (PPO) Δ x
x x 311: Adhesion ■: Solvent resistance to methanol ■: Solvent resistance to gasoline ■; Water resistance V; Hardness

Claims (6)

[Claims] (1) A paint for plastics characterized by dissolving or suspending each component of a dye, a synthetic resin having a group capable of bonding with an epoxy group, and an epoxy silane compound in a solvent. (2) A synthetic tree n having a group capable of bonding with an epoxy group is
Interpolymers of α,β-unsaturated carboxylic acids and lower alkyl esters thereof; The plastic paint according to claim 1, which is an interpolymer with a third polymerizable vinyl monomer. (3) The plastic paint according to claim (1), wherein the synthetic resin having a group capable of bonding with an epoxy group has a molecular weight in the range of 5,000 to 100,000. (4) The paint for plastics according to claim (1), wherein the epoxysilane compound is a compound having the following general formula. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R_1 is a divalent hydrocarbon group of C_1 to C_1_0 or C_2 to C_2 containing at least one ether bond.
C_1_0 is a divalent hydrocarbon group, R_2 and R_3 are C_1 to C_5 hydrocarbon groups, and m is 0 or 1.
, n is 0, 1 or 2. ] (5) The paint for plastics according to claim (1), wherein the plastic is a plastic molded product containing an inorganic filler. (6) The paint for plastics according to claim (1), wherein the plastic is a polypropylene resin molding or a polyphenylene oxide resin molding.